Sina (Nasdaq: SINA) will hold a blog competition to celebrate the 10th anniversary of Hong Kong's return to China from June 12 to July 1. Sina bloggers can participate in the competition by writing about Hong Kong's return to China and publishing their blog entries at publish.sina.com.cn/05/76/576/sign.html. Sina (Nasdaq: SINA) and China Mobile (NYSE: CHL, 941.HK) subsidiary Beijing Mobile also recently launched an essay competition for China Mobile's mobile service brand M-Zone, reports Sina. Internet users can participate in the competition by writing essays about M-Zone and submitting them to jeff.wongcn@gmail.com between now and July 31. Sina has invited five of its top bloggers and two well-known online writers to judge the essays. The winning essays will be posted on Beijing Mobile's official M-Zone blog at Blog.sina.com.cn/bjmzone.